Ok, I had bluetooth modem tethering working great with T-Mobile Pearl, and I've done the same with my Cingular pearl. Anyone know if Im going to be charged some tethering fee if I don't have the Tethered data plan (i.e. I have BIS)?

My hunch is that the phone can't tell the difference between bluetooth DUN and say Opera Mini, but I'd like to know before I ring up $75 prorated dollars.

I'd rather not pay when it works for free. When I went last week to look at the Blackjack, I asked specifically about it. They said that while the tethering plan was officially required, they couldn't really stop us from doing that stuff on our own (i.e. without their tethering software and so forth).